After a cloudy and cool day today, we return to summertime warmth and humidity Sunday, along with showers and thunderstorms (especially in the afternoon and evening). Highs will top out in the 70s and lower 80s.
We expect a brief cool down on Monday, but summertime heat and humidity should return by the end of next week. It's possible that highs will reach 90 degrees by Friday and into next weekend.
[Note that Cape forecast has lower temps than the overall outlook for the Bay State]